docs: def _loadable_models():
      """A dictionary of loadable PyPhi models.
  
      These are stored in this function (instead of module scope) to resolve
      circular import issues.
      """
      classes = [
          pyphi.Direction,
          pyphi.Network,
          pyphi.Subsystem,
          pyphi.Transition,
          pyphi.labels.NodeLabels,
          pyphi.models.Cut,
          pyphi.models.KCut,
          pyphi.models.NullCut,
          pyphi.models.Part,
          pyphi.models.Bipartition,
          pyphi.models.KPartition,
          pyphi.models.Tripartition,
          pyphi.models.RepertoireIrreducibilityAnalysis,
          pyphi.models.MaximallyIrreducibleCauseOrEffect,
          pyphi.models.MaximallyIrreducibleCause,
          pyphi.models.MaximallyIrreducibleEffect,
          pyphi.models.Concept,
          pyphi.models.CauseEffectStructure,
          pyphi.models.SystemIrreducibilityAnalysis,
          pyphi.models.ActualCut,
          pyphi.models.AcRepertoireIrreducibilityAnalysis,
          pyphi.models.CausalLink,
          pyphi.models.Account,
          pyphi.models.AcSystemIrreducibilityAnalysis
      ]
      return {cls.__name__: cls for cls in classes}